Apple, Facebook, eBay, Intel and dozens more American corporations will submit an amicus brief to the Supreme Court today defending marriage equality in light of the upcoming cases on Prop 8 and DOMA.

According to a copy of the brief obtained by Fortune, the companies signing on say that laws like Prop 8 “send an unmistakeable signal that same-sex couples are in some way inferior to opposite-sex couples, a proposition that is anathema to amici’s commitment to equality and fair treatment to all.”

They also made the argument pro-marriage-equality folks bring up all the time, but that conservatives never seem to hear: same-sex marriage is good for business.

Fleshing out that contention, the companies argue: “By singling out a group for less favorable treatment, Proposition 8 impedes businesses from achieving the market’s ideal of efficient operations — particularly in recruiting, hiring, and retaining talented people who are in the best position to operate at their highest capacity. Amici are competing domestically and internationally with companies inside and outside the United States in places where all couples, regardless of whether they are of the same sex, are afforded equal access to marriage.”

Specifically, it suggests that when “potential recruits or employees are members of a same-sex couple,” they “may forgo the opportunity to work in California, and prefer other states (like Iowa, New York, and Massachusetts) or other nations (like Spain, Sweden, Denmark, the Netherlands, Portugal, or Belgium) where they can be married and obtain equal treatment and respect under the law.”

Laws like Prop 8 “leave companies in the untenable position of being compelled implicitly to endorse the second-class status to which their gay and lesbian employees, clients, customers, and business associates are relegated,” the brief argues. “Until the law no longer relegates same-sex couples to second-class status as inferior “domestic partnerships,” our adherence to the law compels us to abide by a distinction that stigmatizes and dehumanizes gay men and lesbians.”

Basically, this is a very wordy way of saying that equality is the only way to go. Everyone’s starting to realize it. It’s only a matter of time before we don’t even have to ask this question anymore.